When I applied for my extension they demanded 3 months in the bank.

Wow non-immigrant o needs to carry 20k into the country in cash?? Even if u have bank accounts and a life already established here?

Mae sai is fun. Lots to do on both sides. Lots of markets and temples.

Also, anyone coming in on a non immigrant o marriage visa and you are not staying in a hotel, you need to complete a tm30 within the 24 hour window or the following business day (if a weekend). Please remember that all northern immigration offices (Chiang Rai, Phayao, Phrea, Lampung and other provinces I've missed in the north) report to Chiang Mai immigration and what Chiang Mai says is the rule of law.

I think the non immigrant o marriage extension needs to be corrected. I obtained a single entry non o from Vientiane not my home country, you do not have to travel home to get it. You can also apply for the extension up to 45 days before the expiry of the non O marriage visa. Though your assessment won't commence till the 30 day window (usually 2 week so).

Also most immigration officers want to see you have the 400k in your account for longer then 2 (usually 3-4 months) and use the money or add onto it.